Evaluation of the growth dynamics of Trichophyton rubrum cultures by morphometry and non-linear curve fitting...

To determine the size of dermatophyte thalli, a point-counting procedure with a square lattice grid is proposed instead of using the one-dimensional diameter as the size parameter. For an analysis of the growth dynamics of such colonies, the area values might be subjected to a non-linear curve-fitting procedure. To demonstrate the method, samples of 15 Trichophyton rubrum strains, isolated from human skin and cultured concomitantly on Sabouraud and Selective agar during a period of 8 weeks, were used. The morphometric assessment of the area of the thalli, subjected to non-linear curve fitting, disclosed only a slight difference in the growth dynamics.